Screw systems

ABSTRACT

A screw system including a plurality of segmented blades. Each blade segment of the plurality of blade segments including a mounting portion and a vane portion. The mounting portion, having a helical length, for removably attaching the blade segment. The vane portion extending from the mounting portion along the helical length thereof. The vane portion having a front surface that is not parallel to a back surface from the mounting portion to a tip of the blade segment, along the helical length.

RELATED APPLICATIONS

This application claims priority and the benefit of U.S. ProvisionalApplication Ser. No. 62/713,740, filed Aug. 2, 2018, entitled “ScrewSystems,” which is hereby incorporated by reference in its entirety.

BACKGROUND

Steel screw turbines (e.g., hydrodynamic screws) exist for producingpower. However, manufacture of these steel turbines is time consumingand they are costly to ship and install. For example, conventional steelturbines may be formed from consecutive annular sections of a steelplate that has been bent to have a blade shape. The annular sections ofthe bent steel plate may be welded to a central steel tube, and adjacentannular sections are also welded together. After welding the annularsections to the central tube and to each other, the welds and/or outsideedges of the bent steel plate may be ground and/or machined. Followingthese operations, the screw may be prepped and painted for appearanceand corrosion resistance. The relatively large and relatively heavysteel turbines may then be shipped fully assembled to a site where acrane may be employed to install the steel turbines for use to generatepower.

The labor-intensive work involved in fabricating the steel turbines istime consuming and costly. Moreover, it is difficult and costly to shipthe fully assembled steel turbines. Further, the maximum flow througheach turbine (and therefore, power output) is physically limited by thelargest allowable diameter which may be transported. Accordingly, thereremains a desire to overcome the limitations of the steel turbinesincluding minimizing the amount and difficulty level of the labor tofabricate a turbine and reducing shipping costs and physical challengesof transportation.

SUMMARY

Screw systems and techniques for manufacturing such systems aredescribed herein. More specifically, this disclosure relates tocomposite screw systems that have a plurality of blade segments, each ofthe plurality of blade segments being removably attachable orpermanently attachable to a shaft. This summary is provided to introducesimplified concepts of composite screw systems, which are furtherdescribed below in the Detailed Description. This summary is notintended to identify essential features of the claimed subject matter,nor is it intended for use in determining the scope of the claimedsubject matter.

In an embodiment, a blade for a screw system includes a blade segmentformed of a composite material. The blade segment may include anintegral mounting portion and a vane portion. The integral mountingportion may have a helical length, for removably attaching the bladesegment to an outside surface of a shaft around which the blade isattachable. The vane portion may extend from the integral mountingportion along the helical length thereof. The vane portion may have afront surface and a back surface. The front surface may not be parallelto the back surface such that a cross section of the blade segmentvaries from the mounting portion to a tip of the blade segment, alongthe helical length.

In another embodiment, a screw system includes a plurality of bladesegments. Each blade segment of the plurality of blade segments mayinclude an integral mounting portion and a vane portion. The integralmounting portion may have a helical length, for removably attaching theblade segment. The vane portion may extend from the integral mountingportion along the helical length thereof, and may have a front surfaceand a back surface, where the front surface may not be parallel to theback surface such that a cross section of the blade segment varies fromthe mounting portion to a tip of the blade segment, along the helicallength. A shaft formed of a composite material may have an outsidesurface for removably attaching the plurality of blade segments thereto,the plurality of blade segments wrapping around the outside surfacealong a helical length. The shaft may include a plurality of holesdisposed in the outside surface along the helical length configured toreceive fasteners and removably attach the plurality of blade segmentsto the shaft from the outside of the shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is set forth with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Theuse of the same reference numbers in different figures indicates similaror identical items.

FIG. 1 illustrates an example screw system operating in a hydrodynamicenvironment to produce power.

FIG. 2 illustrates a perspective view of an example screw system thatmay be implemented in the hydrodynamic environment of FIG. 1 accordingto an embodiment in this disclosure.

FIG. 3 illustrates a perspective view of a first side of a plurality ofblade segments removably detached from a shaft of the screw system, inFIG. 2, according to an embodiment in this disclosure.

FIG. 4 illustrates a perspective view of a second side of the pluralityof blade segments in FIG. 3, according to an embodiment in thisdisclosure.

FIG. 5 illustrates a perspective view of the second side of theplurality of blade segments in FIG. 3 with hidden lines shown in dashedlines, according to an embodiment in this disclosure.

FIG. 6 illustrates a perspective view of separated blade segments of theplurality of blade segments in FIG. 3, according to an embodiment inthis disclosure.

FIG. 7 illustrates a section view of a blade segment of the plurality ofblade segments, in FIG. 4, according to an embodiment in thisdisclosure.

FIG. 8 illustrates a perspective view of a standard inlet blade segmentaccording to an embodiment in this disclosure.

FIG. 9 illustrates a perspective view of an optimized inlet bladesegment according to an embodiment in this disclosure.

FIG. 10 illustrates a partial exploded assembly view of the screwsystem, in FIG. 2, according to an embodiment in this disclosure.

FIG. 11 illustrates a perspective view of an optimized example screwsystem that may be implemented in the hydrodynamic environment of FIG. 1according to an embodiment in this disclosure.

FIG. 12 illustrates a perspective view of a first side (“A” side) of amold according to an embodiment in this disclosure.

FIG. 13 illustrates a perspective view of a second side (“B” side) ofthe mold according to an embodiment in this disclosure.

FIG. 14 illustrates a perspective view of a stack of blade segmentsaccording to an embodiment in this disclosure.

FIGS. 15A and 15B depict a flow diagram illustrating an example processof making a screw system according to an embodiment in this disclosure.

DETAILED DESCRIPTION Overview

This disclosure is directed to screw systems having blade segmentsformed of a composite material, where the blade segments are removablyor permanently attachable to a shaft. In forming the blade segments of acomposite material, the blade segments may be formed via a closed moldsystem formation process, which provides for: consistency andrepeatability in producing the blade segments, higher productivity andlower labor costs in producing the blade segments, and lower consumptionof material in producing the blade segments. The closed mold fabricationprocess is specifically unlike blades of existing Archimedes screws andother claims for removable blades in that the blade segments in thisdisclosure are not formed by rolling, cutting, bending, folding, orwelding. Additionally, fabricating the blades of composite materialsprovides greatly increased corrosion resistance over current steelblades, particularly in wastewater applications where hydrogen sulfideis present. Utilizing gelcoat in the mold as an integral part of themanufacturing process also provides a smooth, reproducible surface withless hydraulic friction and eliminates the need for prepping and finalpainting of the blades and the screw system, as compared with othersteel screws today.

Moreover, because the blade segments are removably attachable to theshaft, the screw systems may be shipped unassembled and subsequentlyassembled in the field reducing an amount of time and a cost ofdeploying the screw systems. The removable blades may also be maintainedor replaced as needed in the field without removing the screw system.

In another example, screw systems include a blade. The blade includes ablade segment formed of a composite material having a mounting portionand a vane portion. The mounting portion may be integral to the blade,and the mounting portion defines a helical length. The mounting portionprovides for removably attaching the blade segment to an outside surfaceof a shaft around which the blade is attachable. The vane portion mayextend from the mounting portion along the helical length thereof. Thevane portion may have a front surface and a back surface. The frontsurface may not be parallel to the back surface such that a crosssection of the blade segment varies from the mounting portion to a tipof the blade segment, along the helical length. Thus, for example, in anembodiment, the vane portion may be tapered from the integral mountingportion to a tip of the blade segment, along the helical length. In viewof the mounting portion, the blade segment may be quickly and easilyattached to the shaft at a reduced cost. Moreover, the vane portion ofthe blade segment is optimized for best performance andmanufacturability.

While this application describes various embodiments of screw systemsused in a hydrodynamic environment to produce power, this is by way ofexample and not limitation. For example, the screw systems may be usedin other fields such as in a hydrodynamic environment to pump water orother fluids, in a hydrodynamic environment as a fishway, in a dryenvironment as a conveyor to move granular materials, in a drillingenvironment as an augur to bore a hole, etc. Further, while thisapplication describes blade segments that are removably attachable to ashaft, the blade segments may be permanently attached to the shaft. Forexample, the blade segments may be bonded to the shaft via an adhesive,a wrap (e.g., composite wrap, fiberglass wrap, an adhesive tape, etc.),an epoxy, etc. Further, and for example, the blade segments may besnap-fit, press fit, interference fit, friction fit, etc. to the shaft.Further, while this application describes a shaft formed of a compositematerial, the shaft may be formed of other material. For example, theshaft may be formed of metal, plastic, wood, ceramic, etc. Further,while this application describes blind holes in the shaft for removablyattaching the blade segments, the shaft could contain through holes,stepped holes, threaded holes, studs, or other fasteners mounted on theshaft to receive the blade segments. Further, while this applicationdescribes blade segments formed via a closed mold system formationprocess, the blade segments may be formed via other processes. Forexample, the blade segments may be formed via a 3D (three-dimensional)printing process, an open mold process, an additive manufacturingprocess, a rapid prototype process, a CNC (computer numerical control)machining process, a casting process, etc.

Illustrative Screw System

FIG. 1 illustrates an example screw system 100 operating in ahydrodynamic environment 102 to produce power. The screw system 100 maybe a screw turbine system. For example, the screw system 100 may be anoptimized composite Archimedes hydrodynamic screw turbine. The screwsystem 100 may have a constant outside diameter of about 6 feet toprovide a flow capacity of about 50 cubic feet per second and mayoperate in hydrodynamic environments having a head drop of 10 feet. Inanother example, the screw system 100 may have a constant outsidediameter of 18 feet to provide a flow capacity of about 600 cubic feetper second and may operate in hydrodynamic environments having a headdrop of 40 feet. The screw system 100 may include an outer trough 108outside of the blade 104.

The screw system 100 may include a blade 104 attached to a shaft 106.For example, the blade 104 may include a plurality of blade segmentsformed of a composite material that are removably attached to the shaft106. The shaft 106 may be formed of a composite material different thanthe composite material forming the plurality of blade segments. Forexample, the shaft 106 may be formed of a multi-layer filament-woundcomposite and the plurality of blade segments may be formed of a closedmolded system composite. The shaft 106 may be formed of a multi-layerfilament-wound pressure pipe. The blade segments may be formed of aresin infused fiber.

FIG. 2 illustrates a perspective view 200 of an example screw system 202that may be implemented in the hydrodynamic environment of FIG. 1according to an embodiment in this disclosure. The screw system 202 maybe the same as the screw system 100 in FIG. 1. The screw system 202 mayinclude at least one or a plurality of blades 204 attached to a shaft206. Each of the plurality of blades 204 may include a plurality ofblade segments 208(1), 208(2), 208(n) attached to the shaft 206. WhileFIG. 2 illustrates the screw system 202 includes four blades 204, thescrew system 202 may include any number of blades (e.g., blade flights).For example, the screw system may include three, four, five, six, etc.blade flights attached to the shaft 206.

In an embodiment, the blade segments 208(1)-208(n) may be substantiallyidentical and are aligned with each other such that the blade segments208(1)-208(n) overlap. For example, a first blade segment may besubstantially identical to a second blade segment and aligned with thesecond blade segment such that at least a portion of the first bladesegment overlaps at least a portion of the second blade segment alongthe helical length when the first and second blade segments areremovably attached to the outside surface of the shaft 206.

In an alternative embodiment, the blade segments 208(1)-208(n) may notbe substantially identical. For example, an optimized inlet bladesegment or an optimized outlet blade segment (discussed below withregard to FIG. 9 and with regard to FIG. 11, respectively) may not besubstantially identical to an adjacent blade segment there between. Forexample, an optimized inlet blade segment or an optimized outlet bladesegment may have a different shape (e.g., a different curve) than ashape (e.g., a curve) of an adjacent blade segment to provide for anoptimized end of the optimized inlet blade segment or an optimized endof the optimized outlet blade segment. An optimized end of the optimizedinlet blade segment or an optimized end of the optimized outlet bladesegment may be reduced or extended to provide less resistance when waterenters or exits the screw system 202.

In an alternative embodiment, the blade segments 208(1)-208(n) may notbe substantially identical. For example, a first blade segment may beformed of a first material, and a second blade segment may be formed ofa second material different than the first material. For example, thefirst blade segment may be formed of a first material including fiber,resin, or coating different than the second blade segment formed of asecond material including a different fiber, a different resin, or adifferent coating. For example, an entry blade segment and/or an exitblade segment may be formed of a stronger material than a materialforming a neighboring blade segment. In another example, the exit bladesegments of a flight of blade segments may be formed of or incorporatestronger materials than the remaining blade segments of the flight ofblade segments. Each blade segment may be tailored to different stressesassociated with each blade segment.

FIG. 3 illustrates a front perspective view 300 of a plurality of bladesegments 302(1), 302(2), and 302(n) that are removably attachable to ashaft such as shaft 206 of the screw system 202, in FIG. 2, according toan embodiment in this disclosure. The plurality of blade segments302(1)-302(n) may be the same as the plurality of blade segments208(1)-208(n). Each blade segment of the plurality of blade segments302(1)-302(n) may be formed of a composite material. Each blade segmentof the plurality of blade segments 302(1)-302(n) may include a mountingportion 304 and a vane portion 306. The mounting portion 304 has ahelical length 308, along which the blade segment is removablyattachable to an outside surface of a shaft (e.g., shaft 206) to form ablade (e.g., blade 204). The vane portion 306 extends from the mountingportion 304 along the helical length 308 thereof. In one example, thevane portion 306 may be tapered from its intersection with the mountingportion 304 to a tip 310 of the vane portion 306 on a blade segment. Thetapered blade segment may have a thickness at the tip 310 that is about50% of the thickness of the root 304. In another example, the vaneportion 306 may not be tapered, where the non-tapered blade segment mayhave a thickness at the tip 310 that is about equal to a thickness ofthe root 304. In another example, the vane portion 306 may have anydifferent cross section other than a taper or non-taper such that atsome or all points the front surface of the vane portion is not parallelto the back surface of the vane portion.

The mounting portion 304 may have a first helicoid shape. The vaneportion 306 may have a second helicoid shape different than the firsthelicoid shape of the mounting portion. The front side of the vaneportion 306 may have a second helicoid shape different than the helicoidshape of the back side of the vane portion.

A flexible material may be arranged between blade segments to controlfluid leakage between blade segments. For example, a flexible materialmay be arranged between a first blade segment and a second blade segmentto control fluid leakage between the first blade segment and the secondblade segment. The flexible material may be disposed along the vaneportion of the first blade segment and the vane portion of the secondblade segment. Further, the flexible material may be applied as a liquidor a solid. The flexible material may be a rubber, a plastic, a fabric,etc.

The flexible material may be arranged on the tip 310 (e.g., outerhelical radius). When the screw system 202 is deployed, the flexiblematerial arranged on the tip 310 may be arranged between the tip 310 ofthe blade segment and an outer trough outside of the blade segment tocontrol fluid leakage between the tip of the blade segment as the screwrotates in the outer trough. Further, the flexible material may beapplied as a liquid or a solid. The flexible material may be a rubber, aplastic, a fabric, etc.

In one example, the helical length 308 may extend about 30, about 45,about 60, about 90, or about 180 degrees of rotation about the outsidesurface of the shaft 206. In another example, the helical length 308 mayextend from at least about 30 degrees to at most about 180 degrees ofrotation about the outside surface of the shaft 206. In another example,the helical length 308 may extend any degrees of rotation about theoutside surface of the shaft 206.

While FIG. 3 illustrates the blade segments 302(1)-302(n) having anL-shaped cross-sectional profile, the blade segments 302(1)-302(n) mayhave other cross-sectional profiles. For example, the blade segments302(1)-302(n) may have a T-shaped profile. For example, the bladesegments 302(1)-302(n) may have another mounting portion extending outaway from the vein portion 306 and opposite to the mounting portion 304.

FIG. 4 illustrates a perspective view 400 of the plurality of bladesegments 302(1)-302(n) in FIG. 3, according to an embodiment in thisdisclosure. The mounting portion 304 may be integrally formed with thevane portion 306. The vane portion 306 may extend from the integralmounting portion 304 along the helical length thereof.

FIG. 5 illustrates a perspective view 500 of the plurality of bladesegments 302(1)-302(n) in FIG. 3 with hidden lines shown in dashedlines, according to an embodiment in this disclosure. FIG. 5 illustratesthe dashed lines where an edge of a blade segment slides over an edge ofanother blade segment to the left. For example, each of the ends of eachblade segment may be shaped substantially the same but in reverse, suchthat a left end of a first blade segment (e.g., a center or middle bladesegment) slips over an end of a second blade segment arranged on theleft side of the first blade segment, and the right end of the firstblade segment slips under an end of a third blade segment arranged onthe right side of the first blade segment. Thus, the respective ends ofblade segments may overlap the adjacent ends of adjacent blade segmentsat an angle of about 45 degrees. Note, however, that the degree of theangled overlapping end is not limited to 45 degrees and may vary asdesired between 0 (no overlap) to 90 (no overlap).

FIG. 6 illustrates a perspective view 600 of separated blade segments302(1) and 302(2) of the plurality of blade segments 302(1)-302(n) inFIG. 3, according to an embodiment in this disclosure. FIG. 6illustrates an end 602 of the blade segment 302(2). As indicated above,the end 602 of the blade segment 302(2) may overlap the end of the bladesegment 302(1) at an angle of about 45 degrees.

FIG. 7 illustrates a section view 700 of a blade segment (e.g., bladesegment 302(2)) of the plurality of blade segments 302(1)-302(n), inFIG. 4, according to an embodiment in this disclosure. Section view 700illustrates the vane portion 306 including a taper 702 from the mountingportion 304 to the tip 310 of the blade segment. For example, the vaneportion 306 reduces in thickness from the mounting portion 304 to thetip 310 of the blade segment. While FIG. 7 illustrates the vane portion306 including a taper 702, the vane portion 306 may have otherthicknesses or shapes. For example, the vane portion may have a frontsurface and a back surface. The front surface may be oriented in adirection or plane that is transverse to the orientation of the backsurface such that the front surface is not oriented parallel to the backsurface and a cross section of the blade segment varies from themounting portion to a tip of the blade segment, along the helicallength.

FIG. 8 illustrates a perspective view 800 of a standard inlet bladesegment 802 according to an embodiment in this disclosure. The standardinlet blade segment 802 may be an entry blade, which may besubstantially the same shape as every other blade segment (e.g., bladesegments 208(1)-208(n) or blade segments 302(1)-302(n) attached to ashaft (e.g., shaft 106 or shaft 206).

FIG. 9 illustrates a perspective view 900 of an optimized inlet bladesegment 902 according to an embodiment in this disclosure. A curve ofthe optimized inlet blade segment 902 may be reduced to provide for anoptimized end of the optimized inlet blade segment 902. The curve may becalculated to be the actual surface of the water as the water enters thescrew system when the blade/turbine is turning, where the screw systemmay run at about a 26-degree angle. By cutting away the beginning of theentry blade to this shape, the water may encounter less resistance whenthe water enters the screw system (the opening or aperture into thescrew system is larger, so water enters the screw system more easilyinstead of the screw system “slicing” at the water as each of the entryblades (e.g., four entry blades of four blade flights) rotate. Theoutlet blade segments, where fluid exits the turbine, may be cut orextended with a rigid flap to reduce noise and sloshing at the exit. Theoptimized outlet blade segment thereby reducing “churning”, splashing,and noise as water exits the turbine.

FIG. 10 illustrates a partial exploded assembly view 1000 of the screwsystem 202, in FIG. 2, according to an embodiment in this disclosure.The screw system 202 may include one or more end plate assemblies 1002and one or more bearing shafts 1004. For example, the screw system 202may include an upper end plate assembly, a lower end plate assembly, anupper bearing shaft, and a lower bearing shaft. The end plate assemblies1002 may be attached to ends of the shaft 206. Any blade segment of anyof the plurality of blade segments 208(1)-208(n) of any one of theblades 204 may be removed from the shaft 206 without removing aneighboring blade segment.

A helical flight of holes 1006 (e.g., blind holes, through holes, etc.)may be disposed in the shaft 206 to provide for removably attaching theblade segments 208(1)-208(n) to the shaft 206 via the outside of theshaft 206 (e.g., without fixing or receiving fasteners from the insideof the shaft 206). For example, the helical flight of holes 1006 mayprovide for attaching the blade segments 208(1)-208(n) to the outsidesurface of the shaft 206 via assembly from the outside of the shaft,without the need to have any fastener (e.g., a nut), equipment orpersonnel on the inside of the shaft. Each blade segment may have blindor through holes (e.g., about one hole per ten degrees of blade segment)drilled and counterbored or countersunk in the mounting portion of theblade segment with a template created from the same “plug” used tocreate the blade segment mold. The exact mating holes may be drilledaround the shaft 206 for mounting all of the blade segments using amulti-axis machining process. The multi-axis machining process mayinclude a drill press mounted on a precision digital x-y table thatalways insures the holes are drilled perpendicular to the surface of theshaft 206 (e.g., the drill press is moved in or out at about a“90-degree” or about a horizontal location on the shaft 206). In anotherexample, the machining process may include match drilling from inside oroutside of the shaft 206. The multi-axis machining process may includean encoder and digital readout on the shaft 206 to know and control atheta (e.g., a rotational position of the shaft 206) while the shaft 206is turned or rotated. The shaft 206 may be turned or rotated viainstalled bearings and/or shafts. The multi-axis machining process mayinclude stopping and/or braking the turning or rotation at very precisepre-calculated positions around the shaft 206. The multi-axis machiningprocess may include, for each hole, the drill press moving up or downthe shaft 206 to a new “x-y” calculated position along the helix. Themulti-axis machining process may provide for indexing, knowing theorientation, and reproducibility for mating of the blade segments208(1)-208(n) to the shaft 206. One or more inserts may be fixed in thehelical flight of holes 1006. The one or more inserts may be disposed toreceive fasteners and removeably attach the blade segments 208(1)-208(n)to the shaft 206. The blade segments 208(1)-208(n) may be removablyattached to the shaft 206 from the outside of the shaft, without havingto secure any fasteners from the inside of the shaft 206. The one ormore inserts may include one or more threaded inserts.

In one example, the formation process used to create the shaft 206 is sorefined that a diameter 1008 of the outside surface of the shaft 206 mayvary no more than about minus ten thousandths of an inch to at mostabout plus ten thousandths of an inch. In another example, the diameter1008 of the outside surface of the shaft 206 may vary no more than aboutminus ⅛ of an inch to at most about plus 1/10 of an inch. Further, theprocess of forming the diameter 1006 of the outside surface of the shaft206 may be finished while the end plate assemblies 1002 are attached tothe ends of the shaft 206. In an embodiment, the shaft 206 may be solidor semi-solid (i.e., a thick shaft cylindrical wall). Alternatively, andaccording to the depicted embodiments, the shaft 206 may be a tube, andmay have a tube wall thickness of about one inch.

FIG. 11 illustrates a perspective view 1100 of an optimized screw system1102 that may be implemented in the hydrodynamic environment of FIG. 1according to an embodiment in this disclosure. The optimized screwsystem 1102 may include optimized inlet blade segments and/or optimizedoutlet blade segments. For example, the optimized inlet blade segment902 may be attached to the shaft as the first blade segment of theplurality of blade segments that form the blades of the optimized screwsystem 1102.

FIG. 12 illustrates a perspective view 1200 of a first side 1202 (“A”side) of a mold. A mounting portion 1204 of fiber may be formed in thefirst side 1202 of the mold such that the mounting portion 1204 has ahelical length 1206 and a first helicoid shape 1208. A vane portion 1210of the fiber may be formed in the first side 1202 of the mold such thatthe vane portion 1210 extends from the mounting portion 1204 along thehelical length 1206 thereof and has a second helicoid shape 1212different than the first helicoid shape 1208. In one example, the vaneportion 1210 may be tapered from the mounting portion 1204 to a tip 1214of the vane portion 1210. In another example, the vane portion may havea front surface and a back surface, where the front surface may not beparallel to the back surface such that a cross section of the bladesegment varies from the mounting portion to a tip of the blade segment,along the helical length. The mounting portion 1204 may be formedintegrally with the vane portion 1210. Subsequent to the moldingprocess, the mounting portion 1204 forms the mounting portion of theblade segment and the vane portion 1210 forms the vane portion of theblade segment.

The fiber of the mounting portion 1204 may include chopped fiber, wovenfiber or fiber mat. The fiber may be loaded into the first side 1202 ofthe mold over a gelcoat 1216. For example, a gelcoat may be applied tothe first side 1202 of the mold, and the fiber may then be loaded intothe first side 1202 of the mold over the gelcoat 1216. A coating may beapplied to the first side 1202 of the mold for increased resistance towear or impact from debris, or to corrosion. For example, a coating maybe applied over the gelcoat 1216 applied to the first side 1202 of themold for increased resistance to wear or impact from debris.

FIG. 13 illustrates a perspective view 1300 of a second side 1302 (“B”side) of the mold. The second side 1302 of the mold may be attached tothe first side 1202 of the mold. For example, the first side 1202 andthe second side 1302 of the mold may be placed together. With the firstside 1202 attached to the second side 1302, the mold may be closed. Themold may be closed via sealing the mold under vacuum or under pressure.

In an embodiment of the blade segment formation process, a resin may beintroduced into the mold. For example, as vacuum pressure is applied tothe sealed mold, a catalyzed resin may be drawn into the mold throughports incorporated in the mold. A resin injection pump may be used toaccelerate the resin infusion process. Upon introduction to the mold,the resin may travel around the mold cavity until the cavity and fiberare filled and resin begins to come out of a return resin port. Thereturn resin port may be arranged in the second side 1302 of the mold.

The mold may remain closed for curing of the resin. The mold may becooled internally or the temperature may be monitored with an infra-redsensor outside of the mold to ensure it does not overheat. Aftersufficient curing has occurred, the mold is opened and a first bladesegment may be left to cool further in the first side 1202 of the moldto prevent any distortion of the first blade segment. After de-moldingthe first blade segment, a flashing may be removed with a router and thegelcoat may be touched up as needed.

The first side 1202 and the second side 1302 of the mold may be utilizedto form additional blade segments, each additional blade segmentsubstantially similar to the first blade segment. For example, the firstside 1202 and the second side 1302 of the mold may be a closed moldsystem capable of reproducing substantially identical blade segments.The closed mold system formation process may be a vacuum process or apressure process. The closed mold system may utilize a flexible secondside 1302 such as a reusable vacuum bag. Further, structural properties,wear properties, corrosion resistance, or surface characteristics may betailored for one or more blade segments via varying materials, resins,or coatings arranged in the closed mold system formation process. Forexample, one or more carbon fiber layers or other materials could beused in the mold to increase the strength to weight ratio of the blade.

FIG. 13 illustrates the gelcoat 1216 may be applied to the second side1302 of the mold. A coating 1304 may be applied to the second side 1302of the mold cavity for increased resistance to wear or impact fromdebris or corrosion. For example, the coating 1304 may be applied forincreased resistance to wear or impact from debris.

FIG. 14 illustrates a perspective view 1400 of a stack 1402 of bladesegments 1404. The blade segments 1404 may be representative of theblade segments 208(1)-208(n) or blade segments 302(1)-302(n). Each bladesegment of the stack of blade segments 1404 may be stacked on anotherblade segment such that the mounting portion (e.g., mounting portion304) of a blade segment interfaces with the mounting portion of anothersecond blade segment, and the vane portion (e.g., vane portion 306) ofthe blade segment interfaces with the vane portion of the other bladesegment. For example, a blade segment may be stackable such that whenstacked with other blade segments, adjacent surfaces are orientedflushly together. In one example, each blade segment of the stack ofblade segments 1404 may include a flashing. The flashing may be afeature resulting from the molding process. In another example, eachblade segment of the stack of blade segments 1404 may be void of theflashing. For example, after the blade segment is de-molded, theflashing may be removed.

Example Method of Making a Screw System

FIG. 15 illustrates an example method 1500 of making a screw system(e.g., screw system 202 or screw system 1102) based at least in part onforming a blade segment (e.g., blade segments 208(1)-208(n), bladesegments 302(1)-302(n), blade segment 802, or blade segment 902)removably attachable to an outside surface of a shaft (e.g., shaft 206).For instance, this process may be performed to produce or manufacture ascrew system having blade segments formed of a composite material, wherethe blade segments are removably attachable to a shaft, which providesfor: consistency, repeatability, higher productivity, and lower costs inproducing the blade segments. Additionally, utilizing gelcoat in themold as an integral part of the manufacturing process provides a smooth,reproducible surface with less hydraulic friction and eliminates theneed for prepping and final painting of the blades, as compared with allsteel screws today.

Further, because the blade segments are removably attachable to theshaft, the screw systems may be shipped unassembled and subsequentlyassembled or replaced in the field reducing an amount of time and a costof deploying and maintaining the screw systems. While FIG. 15illustrates a method of making a screw system used in a hydrodynamicenvironment to produce power, this method may apply to making screwsystems used in other fields such as in a hydrodynamic environment topump water or other fluids, in a hydrodynamic environment as a fishway,in a dry environment as a conveyor to move granular materials, in adrilling environment as an augur to bore a hole, etc. Further, whileFIG. 15 illustrates a method of making screw systems having bladesegments that are removably attachable to a shaft as well as thepost-manufacture step of installation, this method may apply to makingscrew systems having blade segments that are permanently attached to theshaft.

Method 1500 may include operation 1502, which represents applying agelcoat (e.g., gelcoat 1216) to a first side (e.g., first side 1202) ofa mold cavity and/or applying the gelcoat to a second side (e.g., secondside 1302) of the mold cavity. Method 1500 may proceed to operation1504, which represents applying a coating (e.g., coating 1304) to thefirst side of the mold cavity and/or applying the coating to the secondside of the mold cavity for increased resistance to wear or impact fromdebris or corrosion. For example, a hard-facing may be applied to thefirst side of the mold cavity and/or applied to the second side of themold cavity for increased resistance to wear or impact from debris. Thismay be particularly advantageous for the second side because the secondside of the blade segment is expected to have the most friction/wear asit faces the incoming water or fluid flows.

Method 1500 may include an operation 1506, which includes forming, inthe first side of a mold, a mounting portion (e.g., mounting portion1204) of fiber such that the mounting portion has a helical length(e.g., helical length 1206) and a first helicoid shape (e.g., firsthelicoid shape 1208).

Method 1500 may include operation 1508, which includes forming, in thefirst side of the mold, a vane portion (e.g., vane portion 1210) of thefiber such that the vane portion extends from the mounting portion alongthe helical length thereof and has a second helicoid shape (e.g., secondhelicoid shape 1212) different than the first helicoid shape. The vaneportion may be tapered from the mounting portion to a tip (e.g., tip1214) of the vane portion. The vane portion may have other crosssections than a taper. The mounting portion of fiber may be integrallyformed with the vane portion of fiber.

Method 1500 may continue with operation 1510, in which the second sideof the mold is attached to the first side of the mold. For example, thesecond side of the mold is placed on top of the first side of mold.Operation 1510 may be followed by operation 1512, in which the mold isclosed. For example, the mold may be closed via sealing the mold undervacuum.

Method 1500 may continue with operation 1514, which includes introducinga resin into the mold. For example, as vacuum pressure is applied to thesealed mold, a catalyzed resin may be drawn into the mold through portsincorporated in the mold.

Method 1500 may further include operation 1516, which includes curingthe resin. In an embodiment, the mold may remain closed for curing ofthe resin, and the mold may be cooled or the temperature may bemonitored with an infra-red sensor outside of the mold to ensure thatthe mold and/or the blade segment being formed therein does notoverheat.

Method 1500 may include operation 1518, in which the mold is opened, anda first blade segment may be left to cool further in the first side ofthe mold to prevent any distortion of the first blade segment.

In an embodiment, after operation 1518 is finished, the blade segmentmay be de-molded in operation 1520. Operation 1520 may further includeremoving flashing from the de-molded blade segment and touching up thegel-coat as needed. At a time where space is desired to be maximizedand/or for shipping purposes possibly, operation 1520 may be followed byoperation 1522, which includes stacking the blade segments.

As discussed above, although the blade segments may be stacked forstorage or shipping, method 1500 may further include operation 1524,which discusses removably attaching the blade segments to a shaft (e.g.shaft 206). For example, a helical flight of holes (e.g., helical flightof holes 1006) may be disposed in the shaft 206 to provide for removablyattaching the blade segments to the shaft. One or more inserts may befixed in the helical flight of holes 1006 to receive fasteners andremoveably attach the blade segments to the shaft.

CONCLUSION

Although the invention has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the invention is not necessarily limited to the specific featuresor acts described. Rather, the specific features and acts are disclosedas illustrative forms of implementing the invention. For example, whileembodiments are described having certain shapes, sizes, andconfigurations, these shapes, sizes, and configurations are merelyillustrative.

What is claimed is:
 1. A blade for a screw turbine or screw pump system,the blade comprising: a blade segment formed of a composite material,the blade segment including: a mounting portion, having a helicallength, for removably attaching the blade segment to an outside surfaceof a shaft around which the blade is attachable, and a vane portionextending from the mounting portion along the helical length thereof,the vane portion having a front surface and a back surface, wherein thefront surface is not parallel to the back surface such that a crosssection of the blade segment varies from the mounting portion to a tipof the blade segment, along the helical length.
 2. The blade of claim 1,wherein the blade segment is a first blade segment, and wherein theblade further comprises a second blade segment substantially identicalto the first blade segment and aligned with the first blade segment suchthat at least a portion of the first blade segment overlaps at least aportion of the second blade segment along the helical length when thefirst and second blade segments are removably attached to the outsidesurface of the shaft.
 3. The blade of claim 2, further comprising aflexible material arranged between the first blade segment and thesecond blade segment, the flexible material to control fluid leakagebetween the first blade segment and the second blade segment, or theflexible material is attached to the tip of the blade segment to controlleakage around the blade segments and an outer trough.
 4. The blade ofclaim 1, wherein the vane portion is tapered from the mounting portionto a tip of the blade segment, along the helical length.
 5. The blade ofclaim 1, wherein the composite material of the blade segment is a firstcomposite material including a closed molded system composite, andwherein the shaft is formed of a second composite material including amulti-layer filament-wound composite.
 6. The blade of claim 1, whereinthe surface includes an integral coating molded thereto for increasedresistance to wear resulting from incoming fluid flow or debris, orincreased resistance to corrosion.
 7. The blade of claim 1, wherein thehelical length extends from at least about 30 degrees to at most about180 degrees of rotation about the outside surface of the shaft.
 8. Theblade of claim 1, wherein the blade segment is a first blade segment,the blade further comprises a second blade segment, and wherein thefirst blade segment is substantially identically shaped to the secondblade segment via a closed mold system formation process.
 9. A screwturbine or screw pump system, comprising: a plurality of blade segments,each blade segment of the plurality of blade segments including: amounting portion, having a helical length, for removably attaching theblade segment, and a vane portion extending from the mounting portionalong the helical length thereof; and a shaft having an outside surfacefor removably attaching the plurality of blade segments thereto, theplurality of blade segments wrapping around the outside surface along ahelical length, the shaft including a plurality of holes disposed in theoutside surface along the helical length, the plurality of holesconfigured to receive fasteners and removably attach the plurality ofblade segments.
 10. The screw turbine or screw pump system of claim 9,wherein a diameter of the outside surface of the shaft varies no morethan about minus thirty thousandths of an inch to at most about plusthirty thousandths of an inch.
 11. The screw turbine or screw pumpsystem of claim 9, further comprising one or more inserts fixed in oneor more of the plurality of holes, the inserts to receive the fastenersand removeably attach the plurality of blade segments from outside ofthe shaft.
 12. The screw turbine or screw pump system of claim 9,wherein the shaft is formed of a composite material.
 13. The screwturbine or screw pump system of claim 9, wherein the plurality of bladesegments includes a first blade segment formed of a first material, anda second blade segment formed of a second material different than thefirst material.
 14. The screw turbine or screw pump system of claim 9,further comprising: a first end plate attached to a first end of theshaft; and a second end plate attached to a second end of the shaft,wherein a diameter of the outside surface of the shaft is finished whilethe first and second end plates are attached to the first and secondends of the shaft.
 15. The screw turbine or screw pump system of claim9, wherein among the plurality of blade segments, a shape of a bladesegment for an entry position or an exit position on the shaft isdistinct from a shape of a blade segment disposed between the entryposition and the exit position.
 16. A method of making a screw turbinesystem, the method comprising: forming a blade segment that is removablyattachable to an outside surface of a shaft, the blade segment includinga mounting portion and a vane portion, and the forming of the bladesegment including: forming, in a first side of a mold, the mountingportion of fiber such that the mounting portion has a helical length anda first helicoid shape, forming, in the first side of the mold, the vaneportion of fiber such that the vane portion extends from the mountingportion along the helical length thereof and has a second helicoid shapedifferent than the first helicoid shape, the vane portion having a frontsurface and a back surface, whereby the front surface is not parallel tothe back surface such that a cross section of the blade segment variesfrom the mounting portion to a tip of the blade segment, along thehelical length, attaching a second side of the mold to the first side ofthe mold, closing the mold, and introducing a resin into the mold,wherein a material used for forming the vane portion and the mountingportion, respectively, is selected based at least in part, on physicaland/or structural characteristics specific to a location where the screwturbine system is to be implemented.
 17. The method of claim 16, whereinthe second side of the mold is a vacuum bag or other non-rigid surface.18. The method of claim 16, wherein the forming of the blade segmentfurther includes: applying a gelcoat to the first side of the mold, orapplying a gelcoat to the second side of the mold.
 19. The method ofclaim 16, wherein the forming of the blade segment further includesapplying a coating to the first side of the mold for increasedresistance to wear or impact from debris or corrosion, or applying acoating to the second side of the mold for increased resistance to wearor impact from debris or corrosion.
 20. The method of claim 16, whereinthe blade segment is a first blade segment, and wherein the methodfurther comprises: forming a second blade segment substantiallyidentical to the first blade segment, forming the shaft, and removablyattaching the first blade segment and the second blade segment to theoutside surface of the shaft such that at least a portion of the firstblade segment overlaps at least a portion of the second blade segmentalong the helical length.